In a battery state monitoring circuit and a battery device using the same, even if a charge inhibiting signal is inputted to a microcomputer control terminal, a lock mode is prevented from occurring in which both a charge control transistor and a discharge control transistor are turned OFF and a battery voltage can not be supplied to a load. A circuit is structured such that even if the charge inhibiting signal is inputted to the microcomputer control terminal, in the case where the overcurrent voltage detection terminal comes to have the overcurrent detection voltage, the charge inhibiting signal of the microcomputer control terminal is cancelled.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A battery state monitoring circuit for controlling charging and discharging of a secondary battery in a battery device having one or more secondary batteries connected to external connection terminals and a charging switch and a discharging switch connected between the secondary batteries and the external connection terminals, comprising: an overcharge detection circuit for producing an overcharge signal for turning off the charging switch when the secondary battery is in an overcharged state; an overcurrent detection circuit for producing an overcurrent signal for turning off the discharging switch when the secondary battery is in an overcurrent state; and a circuit for canceling the overcharge signal to turn on the charging switch to permit charging of the secondary battery when the overcurrent state is detected during a period of time when the overcharge signal is being output.
2. A battery state monitoring circuit according to claim 1 ; further comprising a microcomputer input terminal for receiving an overcharge signal from a microcomputer to inhibit charging of the secondary battery.
3. A battery state monitoring circuit according to claim 2 ; wherein the circuit for canceling the overcharge signal inhibits the overcharge signal produced by the microcomputer and not the overcharge signal produced by the overcharge detection circuit.
4. A battery state monitoring circuit according to claim 2 ; wherein the circuit for canceling the overcharge signal comprises an inverter for inverting the overcharge signal output by the microcomputer, a NOR circuit for receiving output signals of the inverter and the overcurrent detection circuit as inputs, and an OR circuit for receiving output signals of the NOR circuit and the overcharge detection circuit as inputs and producing an output signal supplied to the charging switch.
5. A battery state monitoring circuit according to claim 2 ; wherein the circuit for canceling the overcharge signal comprises a first NOR circuit for receiving an output signal of the overcharge detection circuit and the overcharge signal output by the microcomputer as inputs, a second NOR circuit for receiving output signals of the overcurrent detection circuit and the first NOR circuit as inputs and producing an output signal supplied to the charging switch.
6. A battery state monitoring circuit according to claim 5 ; further comprising a delay circuit interposed between the output of the second NOR circuit and the charging switch.
7. A rechargeable battery device comprising: a rechargeable secondary battery; external connection terminals connectable to the secondary battery, to a load driven by the secondary battery, and to a charger for charging the secondary battery; a charge switch for selectively disconnecting the secondary battery from the external connection terminals; a discharge switch for selectively disconnecting the secondary battery from the external connection terminals; an overcharge detecting circuit for detecting an overcharged state of the secondary battery and generating an overcharge signal to turn off the charge switch when the overcharged state is detected; an overcurrent detection circuit for detecting an overcurrent state of the secondary battery and generating an overcurrent signal to turn off the discharge switch when the overcurrent state is detected; and a circuit for canceling the overcharge signal to turn on the charge switch when the overcurrent state is detected during a period of time when the overcharge signal is being output.
8. A rechargeable battery device according to claim 7 ; further comprising a microcomputer input terminal for receiving an overcharge signal from a microcomputer to inhibit charging of the secondary battery.
9. A rechargeable battery device according to claim 8 ; wherein the circuit for canceling the overcharge signal inhibits the overcharge signal produced by the microcomputer and not the overcharge signal produced by the overcharge detection circuit.
10. A rechargeable battery device according to claim 8 ; wherein the circuit for canceling the overcharge signal comprises an inverter for inverting the overcharge signal output by the microcomputer, a NOR circuit for receiving output signals of the inverter and the overcurrent detection circuit as inputs, and an OR circuit for receiving output signals of the NOR circuit and the overcharge detection circuit as inputs and producing an output signal supplied to the charging switch.
11. A rechargeable battery device according to claim 8 ; wherein the circuit for canceling the overcharge signal comprises a first NOR circuit for receiving an output signal of the overcharge detection circuit and the overcharge signal output by the microcomputer as inputs, a second NOR circuit for receiving output signals of the overcurrent detection circuit and the first NOR circuit as inputs and producing an output signal supplied to the charging switch.
12. A rechargeable battery device according to claim 11 ; further comprising a delay circuit interposed between the output of the second NOR circuit and the charging switch.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
February 14, 2002
March 15, 2005
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